Torque controlling device



Am "F, H956 P. E. sci-1mm TORQUE CONTROLLING DEVICE Filed Dec. 7, 1953 I Y 25 29 I INVENTOR. Pau/ E. Jc/vm/a BY W A TTORNE Y United States Patent .0

TORQUE CONTROLLING DEVICE Paul E. Schmid, Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tex., a corporation of Texas Application December 7, 1953, Serial No. 396,680

1 Claim. (Cl. 64--30) This invention relates broadly to a torque controlling device, but more particularly to an adjustable drive clutch suitable as a wrench or screw driver attachment by means of which the torque applies to a nut or screw may be governed.

One object of this invention is to produce a device which can be used as an adaptor to a power actuated wrench or the like to insure uniformity of torque applied to the work.

Another object of this invention is to provide a power actuated wrench or the like with an adaptor automatically controlling the torque applied to the work, thereby eliminating the human element involved when tightening nuts, screws or the like.

Another object of this invention is to provide a power actuated wrench or the like with a device or adaptor automatcially enabling relative rotation between the driving and driven shafts when a predetermined torque has been reached.

Another object of this invention is to provide such a torque adaptor comprising a minimum number of parts, of simple construction which will efliciently perform the work intended.

Another object of this invention is to provide a torque adaptor with adjustable means readily accessible through which the extent of torque transferable from one end of the unit to the other may be controlled.

Another object of this invention is to provide such an adaptor which can be quickly and easily connected with a power actuated wrench or the like.

Other objects of this invention will be apparent from the following detailed description, wherein Similar characters of reference designate corresponding parts, and wherein:

Figure 1 is a side elevational view of a power actuated wrench embodying the invention.

Figure 2 is an enlarged longitudinal sectional view taken through the torque controlling device or adaptor.

Figure 3 is a cross-sectional view taken on line 3-3 in Figure 2.

Referring to the drawing, represents a power actuated rotary tool, such as a wrench, screw driver or the like, having a drive shaft 11 extending from one end of the tool and preferably terminated by a square to normally receive a work engaging socket. In the present construction, the square end of the tool shaft 11 fits closely within the square socket 12 provided Within the shank 13 of a cup shaped casing 14. The interior of casing 14 is provided with a cylindrical fiat bottom bore 15, the central portion of its bottom wall 9 being recessed to form a seat 16 accommodating a relatively large antifriction ball 17. A pair of alike sleeves 18 and 19 are closely fitted within the casing bore with a space between the inner ends thereof enabling longitudinal movement of one relative to the other. The interior of both sleeves, leading from the inner ends thereof, are inwardly tapered to form two opposed inwardly tapered seats or wedge surfaces 20 and '21 respectively. A plurality of friction shoes 22 are encompassed within the wedge surfaces 20 and 21. They extend longitudinally substantially from the bottom end of one wedge surface to the other, and are preferably made from a sleeve cut longitudinally into equal sections. The exterior of the shoes 22, leading from the outer ends thereof, are outwardly tapered to fit closely within the wedge surfaces 20 and 21 of the sleeves 18 and 19, while the interior thereof are parts or sections of a perfectly cylindrical wall adapted to fit closely on a driven shaft 23. This last shaft extends longitudinally from the ball 17 through the sleeves 18 and 19 in coaxial alignment with the driving shaft 11 of the tool 10, and has its inner end resting against the ball 17 while its outer end is formed as a square shank 24 adapted to, receive a work engaging socket or the like. Near its shank 24, the shaft 23 is formed with an annular recess 25 accommodating the inner edge portion of a retaining washer 26, made of two halves, and clamped between the outer end of the sleeve 18 and the bottom of a gland or cup shaped adjusting nut 27. This nut is screwed on the casing 14 with relatively fine screw threads 28, and is intended to exert axial pressure on the sleeves 18 and 19, that is, between its bottom wall 29 acting on the outer end of the sleeve 18 through the washer 26, while the outer end of the sleeve 19 rests against the bottom 9 of the casing bore 15.

In practice, the driven shaft 23 is preferably made of a steel alloy, hardened and polished; the friction shoes 22 of hard bronze impregnated with graphite particles and the sleeves 18 and 19 of case hardened steel.

In the operation of the device, torque from the tool or driving shaft 11 is transmitted to the work performing driven shaft 23 by frictional engagement of the friction shoes 22 on the shaft 23. As the friction controlling gland or nut 27 is screwed or unscrewed on the casing 14, that is, as it is moved axially relative to the casing 14 in one or the other direction, it will subject the sleeves or wedge members 18 and 19 to more or less axial pressure tending to move them toward each other, thereby causing their tapered or wedge surfaces 20 and 21 to act on the correspondingly tapered external surfaces of the shoes 22 to exert more or less inward radial pressure on the shoes to vary the extent of their frictional engagement with the shaft 23. It will be understood that since the axial forces applied on the wedge members 18 and 19 tend to move them toward each other, the forces are in opposite directions and are translated into inward radial forces of the friction shoes without imparting axial forces to the shoes tending to move them axially on the driven member 23.

Because the angle of the cooperative wedge surfaces between the shoes 22 and the sleeves 18 and 19 is relatively small, only a relatively small tightening force of the nut 27 is required to produce a substantial inward radial force or pressure of the shoes 22 on the driven shaft 23. It will be understood that the adjusting nut 27 may be set for any desired torque of the driven shaft 23 equal to or below that of the driving shaft 11, and that the torque of the driven shaft 23 will remain constant for each setting of the torque adjusting nut 27. When the torque of the driving shaft exceeds the desired torque of the driven shaft 23 for which the nut 27 has been set, the shoes 22 will simply slip over the shaft 23.

The entire device is so designed as to subject only the friction shoes 22 to possible wear, which shoes can readily be replaced without necessitating the use of any special tools.

The details of structure and arrangement of parts shown and described may be variously changed and 3 modified without departing from the spirit and scope of the inventiOIl.

I claim:

In a device of the character described a pair of cup shaped screw threaded cooperating inner and outer elements having bottom walls movable axially toward each other upon rotation of one element relative to the Qther in one direction, one of said elements being adapted to be connected to a rotatable driving shaft, a driven shaft extending through the end wall of the other of said elements formed with an annular recess positioned radially within the bottom wall of said other element, a retaining washer positioned against the bottom wall of said other element extending into the said annular recess limiting axial motion of said driven shaft relative to said 15 elements, a thrust member between one of said elements and said driven shaft, a plurality of friction shoes loosely within said inner element adapted to bear radially on said driven shaft for frictionally transmitting torque thereto, a pair of wedge members within said one element engaged by said retaining washer and the bottom wall .of said one element and movable thereby toward each other upon rotation between said elements in said one direction, and inclined cooperating surfaces between said shoes and each member adapted to translate the movement of said members toward each other into radial pressure of said shoes on said drive shaft.

References Cited in the file of this patent UNITED STATES PATENTS 442,230 Libby Dec. 9, 189.0

859,976 Procunier July 16, 1907 1,107,483 Bohlig Aug. 18, 1914 2,454,098 Schmidt Nov. 16, 1948 2,610,066 Pigott Sept. 9, 1952 FOREIGN PATENTS 182 Great Britain Jan. 3, 1908 

